HPV blood test vs. Pap smear: Which is better?

Human papillomavirus (HPV) blood tests and Pap smear tests are methods for detecting cervical cancer. Doctors may recommend a person has both tests to check for cervical cancer.

Cervical cancer is preventable if doctors can identify it early. Effective cervical cancer screening allows doctors to detect the disease before it grows and spreads to other areas.

Cervical cancer is the fourth most common cancer in women. Almost all of these cases link to persistent infections with high-risk HPV. Cervical cancer screening includes an HPV test, a Pap smear, or both.

About HPV

HPVs are a large group of viruses. HPV is the most widespread sexually transmitted infection in the United States.

The type of HPV that causes genital warts is not the same virus that causes cancers. Most HPV types are skin HPVs, which cause common warts. On the other hand, mucosal HPVs target and live on mucosal surfaces.

Mucosal cells line body parts that open to the outside, such as the vagina and anus. Doctors may also refer to mucosal types of HPV as genital HPV because they typically infect these areas.

Genital HPV can be low risk, which causes genital warts but rarely causes cancer. Or it may be high risk, meaning it is more likely to cause cancer.

A person can get HPV through skin-to-skin contact. A person who has vaginal, anal, or oral sex with someone who has the virus can contract HPV.

HPV can cause genital warts and certain cancers. These include:

  • cervical cancer
  • vaginal cancer
  • vulvar cancer
  • penile cancer
  • anal cancer
  • tongue cancer
  • mouth and throat cancer
  • tonsil cancer

About blood tests for HPV

HPV does not spread through blood or bodily fluids such as semen. There is no blood, urine, anal, or oral swab that can detect HPV.

The only way to detect HPV is by viewing cell samples from the cervix under a microscope. This is because the virus passes through skin-to-skin contact and infects the skin and mucosal cells.

But a 2019 animal study discovered that HPV could cause infections through blood.

In addition, a 2020 study found a pinprick blood test to be effective in the early detection of antibodies for HPV 16. This type of HPV is responsible for most HPV-related head and neck cancers and 70% of cervical cancers.

Differences between a precancerous cervical cell and HPV

Since HPV is a widespread viral infection, many people who are sexually active are likely to be infected at some point in their lives. The body’s immune system often clears the virus within a few months to 2 years.

Some HPV types may linger. A persistent, long-lasting, untreated HPV infection may turn normal cells into abnormal ones, which doctors call precancerous cells.

Without detection, these cells will continue to grow and multiply, causing cancer. But it typically takes 10–20 years or more before precancerous cells develop into a tumor.

Pap smear vs. HPV test

Pap smears detect abnormal cells, which can be precancerous or cancerous. On the other hand, an HPV test checks for the DNA or RNA of cells to see if people have a high-risk HPV infection that can cause cervical cancer.

Should they be used together?

Doctors may use Pap smears and HPV tests to screen for cervical cancer.

In their 2020 guidelines on cervical cancer screening, the ACS recommends that people with a cervix get a primary HPV test every 5 years between ages 25–65 years. It also recommends an HPV/Pap co-test every 5 years, or Pap test alone every 3 years if HPV testing alone is unavailable.

What to expect during each test

Doctors usually do both tests during a pelvic exam. During this, a person lies on an exam table, bending their knees and using the surface to support their feet.

The doctor inserts a plastic or metal device in the vagina to widen it and provide a clear view of the upper vagina and cervix.

The doctor then uses a brush to collect cell and mucus samples from the cervix, places them in a special fluid, and sends them to a lab for analysis.

Doctors may use the same sample for both tests.

Discussing results with a doctor

Labs usually release results within 1–3 weeks. If they find something abnormal in the results, a doctor will contact the person to discuss their test results.

The doctor will talk about the person’s risk and the next course of action. Pap smear results can be:

  • Normal: No abnormal cell changes in the cervix.
  • Unclear: Cervical cells could be abnormal, but it is unclear whether this relates to HPV. An unclear result can be due to pregnancy, an infection, or menopause.
  • Abnormal: There are cervical changes. This is likely the result of HPV and can be low grade or high grade. This result may also indicate cancer.

On the other hand, HPV tests can be positive, meaning high-risk HPV is present, or negative, meaning high-risk HPV is not present.

If a person receives a positive result, the doctor may recommend:

  • waiting for 6–12 months before getting a repeat test
  • getting a colposcopy, a test that aims to find abnormal cells in the cervix, usually after an abnormal Pap result
  • getting a biopsy, where a doctor removes a small tissue sample to send to the lab for analysis
  • receiving treatment for high-grade cervical changes
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